Piston



lsept..s,1936. R. E. DAY 2,053,324y

l y l A' PIsToN Filed NOV. 7, 1952 f6/fg; HUI NM1 5LP QLD E4 Hag] Z-I'. hay.

Patented Sept. 8, 1936 UNITED STATES PATENT OFFICE Claims.

This invention relates to pistons for internal combustion engines, an object of the invention being to control the diameter of the skirt or bearing portions of. the piston independently of cyl- 5 inder wall pressure through the utilization of forces available on account of the relative movement of the wrist pin bosses caused by head expansion and contraction.

A further object of the invention is to provide a piston having a contractible bearing section at one or both sides, and wherein means preferably in the form of diagonal oppositely extending struts is provided and so arranged that the outward movement .of the bosses resulting from head expansion will transmit through these struts forces effective to contract the skirt bearing portions, whereby control of the skirt diameter may be obtained under all operating conditions.

Other objects of. this invention will appear in the following description and appended claims, reference being had to the accompanying drawing forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

Fig. l is a side elevation illustrating a piston embodying the present invention.

Fig. 2 is a horizontal section taken through lines 2 2 of Fig. 1 in the direction of the arrows.

Fig. 3 is a horizontal section taken through lines 3-3 of Fig. 1 in the direction of the arrows.

Fig. i is a vertical section taken through lines 4-4 of Fig. l in the direction .of the arrows.

Fig. 5 is a vertical section taken through lines 5-5 of Fig. 4 in the direction of the arrows.

Before explaining in detail the present invention it is to be understood that the invention is not limited in its applicationto the details .of construction and arrangement of parts illustrated in the accompanying drawing, since the invention is capable of other embodiments and of being practiced or carried out in Various ways. Also it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation, and it 45 is not intended to limit the invention claimed herein beyond the requirements .of the prior art.

Referring to the drawing, wherein there is illustrated one embodiment of the invention, the piston in this instance is preferably formed in 50 a single casting of aluminum alloy, although it is understood that the invention is not limited to this method of. producing the piston nor to the particular material utilized. The piston comprises a head havinga top portion 9 which directly receives the force of the explosion in the engine cylinder, and also comprises an annular depending flange IIl adapted to be machined to provide ring grooves II. The flange or side portion IIJ of the head is exten-ded downwardly at diametrically opposite sides to provide exteriorly curved supports I2 and I3 within which are cast a pair of opposed wrist pin bosses I4 and I5 which have alined openings to receive the wrist pin. This portion of the piston structure is strengthened by means of reinforcing ribs I6 which extend interiorly across the head and integrally embrace opposite sides of the boss-es. These ribs preferably have extensions Ia below the bosses.

The piston skirt proper is formed with opposed bearing surfaces extending on .opposite sides of the piston between the bosses. These bearing surfaces, in the present instance, are mainly in the form of slipper sections. The bearing section I IV at one side of the piston is preferably continuous and is supported from the head through an integral extension I'I'a. This bearing portion is partially separated from the head at opposite sides of the supporting portion I'Ia by means of horizontal annular slots I8.

The lower part of the skirt section I'I is integrally united with circumferential bearing portions !9 disposed below and spaced from the boss supports I3, these bearing portions being in the form of bands forming substantially a complete skirt portion around the lower end of the piston. Diametrically opposite the skirt section I'I are two main bearing portions 28 and 2| which are divided vertically by means of. a zigzag slot 22. The upper edges of the sections and 2| are also separated from the head by means of a horizontal slot 23. The cutting 22 at this side of the piston extends continuously from the air gap 23 through the lower bearing portion I9 to the lower edge of the piston. In the present embodiment the bearing portion 2D is formed with a projecting tongue or extension 26a, and this part is joined to the boss I5 by means of a horizontal strut `or web 24 which spans the slot 22. The bearing portion 2I in turn is provided with two tongue or projecting portions 2Ia and 2lb located above and below the part Za and separated therefrom by apart of the zigzag slot 22. 'The bearing portion 2| is integrally joined to the boss I4 by means of a horizontal strut or web 21, the latter having upper and lower projecting portions 25 and 26 which span the slot 22 and are integrally joined at their Aends to the projecting portions 2Ia and 2lb respectively.

From the forego-ing it will be seen that one side of the skirt is divided vertically into a pair of bearing portions 20 and 2l The bearing portion 20 which lies in the transverse zone of the boss I4 is connected to the boss I5, mo-re remote from the bearing portion 20, by means of the diagonal strut 24. portion 2|, which lies in the transverse zone of boss I5, is joined to the boss I4, more remote therefrom, by means of the diagonal strut 21. The struts 24 and 21, the latter including the parts 25 and 26, are preferably curved so as to ap- In like manner the bearing r proximate the curvature of the skirt portions 20 and 2l. The latter, however, are normally incapable, to any substantial extent, of independent yielding mo-vement due to the cross relation of the struts 24 and 2. In other words, the skirt portion 2Q, 2l is normally non-flexible when cornpression forces are applied directly to the skirt.

The bearing portion Il is preferably reinforced to resist distortion by means of a rib 28, and for like reasons the lower edge oi the skirt is flanged at 29.

The present invention provides a means for controlling the expansion of theY skirtVnot'by cylinder wall pressure, but solely through the medium of forces transmitted as a result of the outward or inward movement of the bosses caused by the expansion or contraction ofthe piston head under temperature changes. Y It will be seen that when the bosses I4 and i5 are moved apart as a result of the head expansion, the boss I4 through the strut 2d will tend to pull the bearing portion 29 inwardly and circumferentially. In like manner the boss l5, when moved outwardly, will, through the strut 21, pull the skirt section 2! inwardly and circumferentially. Thus, the outward mov-ement of the bosses will pull the bearing po-rtions 2t and 2l together in a transverse manner, this being permitted by the slot 22. Consequently, the arrangement is such that the expansion of the head will merelyresult in'maintaining the skirt diameter constant thus preventing the skirt from expanding against the cylinder wall. The piston may be initially fitted closely in the cylinder when cold, whereas under operating conditions the tendency of the skirt to expand with the head against the cylinder wall will be prevented since the normal skirt expansion will be counteracted by the contraction of the bearing portions 2t? and 2| resulting from the forces transmitted thereto from the bosses through the struts 2d and 2li.

I claim:

l. A piston co-mprising a head, wrist pin bosses and a depending skirt, said skirt having a bearing face at one side between the bosses formed with an upright slot to provide contractible sections, and struts extending from the bosses to said sections to draw said sections together circumferentially when the bosses are moved apart,`said struts each spanning said upright slot.

2. A piston comprising a head, wrist pin bosses and a depending skirt, said skirt having a bearingv face at one side between the bosses formed with a vertical slot to provide co-ntractible sections, and struts extending diagonally from the bosses to said sections and arranged to draw said sections together circumferentially when the bosses are moved apart, said struts each spanning said vertical slot.

3. A piston comprising a head, wrist pin bosses and a depending skirt, said skirt having a bearing face at one side between the bosses formed with a vertical slot to providecontractible sections, and a strut extending from each boss to one of said sections and spanning said slot, said struts being arranged to draw said sections to-v gether when the bosses are moved apart through head expansion.

4. A piston comprising a head, wrist pin bosses supported from the head, and a skirt, said skirt at one side between the bosses having a pair of contractible bearing sections provided with interntting circumferential projecting portions separated by a zigzag slot, and struts extending from the bosses to said sections and each having a curvature approximating the curvature of the skirt, said struts being arranged to contract said sections, one independently of the other, when the bosses are moved apart through head expansion.

5. A piston comprising a head, wrist pin bosses supported therefrom, a skirt having at one side between the bosses a pair of vertical bearing portions provided with staggered intertting extensions vseparated by an irregular slot, diagonal struts extending from the bosses to the bearing portions and arranged to lessen the expansion of the skirt diameter by relatively moving said bearing portions when the bosses move apart relatively to each other. Y

6. A piston comprising a head, a skirt, wrist pin bosses supported from the head, said skirt at one side thereof being separated by a vertical slot to form two adjacent bearing portions, a strut connecting each boss with the bearing portion at the far side of said vertical slot, said struts being arranged to draw said bearing portions together when the bosses are moved apart through head expansion. Y

7. A piston comprising a head, a skirt, and wrist pin bosses connected to the head, said skirt at one side being vertically separated by a zigzag slot between the bosses to provide two adjacent bearing portions, a pair of independently movable struts, each of said struts connectingY one of said bearing portions with the boss lying in the transverse zone of the other bearing portion.

8. A piston comprising a head, a skirt, and wrist 'pin 'bosses connected to the head, said skirt at one side being vertically separated to provide two adjacent .bearing portions, a strut Vconnecting each boss with the bearing portion at the far side ofV the vertical separation Ybetween said bearing portions, said bearing portions being normally rigid against movement under pressure and said struts being arranged to move said bearing portions toward each other through forces transmitted from the bosses when the latter are moved apart by head expansion.

9. A piston comprising a head having depending integral supports, a pair of alined wrist pin bosses carried by said supports, a skirt comprising a bearing section at one side integrally joined to-the head and a bearing section at the other side separated from the head, said last bearing section being divided longitudinally into two adjacent contractible bearing portions, and a strut extending laterally fromreach boss to the bearing portion at the far side of the longitudinal division, said struts being effective to maintain said bearing portions substantially non-yieldable under external pressure while operating to transmit oppositely directed forces tothe bearing portions from the bosses. Y

10. A piston comprising a head, wrist pin bosses supported therefrom, a skirt having at one side between the bosses a pair of bearing portions provided with intertting projections separated by a zigzag slot, diagonal strut members extending in close proximity to the inner face of the bearing portions from the bosses to said bearing portions and arranged to lessen the expansion of the skirt diameter by relatively moving said bearing portions when the bosses move apart relatively to one another. Y l

RAY E. DAY. 

